Crane games have been a popular fixture in amusement arcades for many years. These games generally provide a player, who pays some predetermined amount for each game, with an opportunity to use a traversing mechanism to move a grasping mechanism laterally above a bin filled with prizes so as to attempt to select one of the prizes below the grasping mechanism. The grasping mechanism is then lowered into the bin where it may grasp one of the prizes which can then be lifted upwards, moved laterally until it is over a delivery chute, and dropped into the chute from wihch it can be removed by the player. The prizes are often soft stuffed toys and are generally deformable so as to make them easier to grasp with a clawed mechanism.
Prior art crane games commonly have only one or two layers of prizes in their bins. This requires an operator to frequently open the game's housing and load additional merchandise to replace items delivered to players. Attempts to reduce the frequency of service calls for re-loading by simply using a deeper bin and piling the prizes higher have not worked well because both the weight of prizes near the top of the pile and the tamping effect of the dropping claw compact the deformable prizes stored below them. After the uppermost prizes are removed during play, the remaining prizes are so thoroughly jammed together that the grasping mechanism is unable to lift one of them out of the compacted and interlocked pile.
Whether or not the claw mechanism is attempting to pick up a lone prize resting on a floor of a bin or to extricate one of many prizes from a pile of prizes, players of crane games are often concerned about the degree to which the claw mechanism performs reliably and consistently. Stubben (U.S. Pat. No. 6,283,475) describes a solenoid-actuated crane game claw in which a input from a game operator, rather than from a player, is used to select a solenoid drive current that determines the closing force of the claw. Stubben does not teach the use of a motor and gear drive for actuating the claw. Moreover, the only controlled parameter in Stubben's apparatus is a solenoid drive current. In addition, the operator input in Stubben's apparatus is of a conventional type that allows the value of the controlled parameter to be hidden from a user of the game.
A known crane game grasping mechanism uses a worm gear turned by the motor to drive a worm gear follower attached to the claws so that the claws move between an open and a closed position. Travel-limiting stops at both ends of the worm are used by the game operator to set the open limit and closed limit positions. When the worm gear nut attached to the claws runs into either of the travel-limiting stops, its progress along the worm is stopped and the motor stalls out. This arrangement limits the sizes of both the largest and smallest prizes that can be picked up, and coacts with the elastic properties of the prizes to provide a range of gripping forces. The gripping force, however, is not directly controlled.